Laser-assisted coherent atomic tunneling between two trapped Bose-Einstein condensates

We describe the coherent atomic tunneling between two Bose-Einstein condensates confined in a double-well potential, whose zero-point energies are modulated by a small oscillation of the barrier-laser position. The coupled-mode equations derived from the Gross-Pitaevskii equation describe the dynamics in terms of the population imbalance as a function of the modulation amplitude of the zero-point energies normalized by the modulation frequency. It is predicted that the modulation of the zero-point energies induces the laser-assisted tunneling (LAT) and the resonant peaks of the LATs are remarkably shifted in energy by the nonlinearity due to the many-body interactions. It is also shown that the threshold of the nonlinear self-interaction for the spontaneous symmetry breaking is modified by the potential modulations. These features are qualitatively explained by considering that the coupling (or tunneling) coefficient K is effectively given by $\overrightarrow{K}{K}_n^{\mathrm{eff}}{=J}_n{(E}_{\omega }/\omega )K$ for the $n\mathrm{th}$ LAT under the influence of the potential modulations, where $E_{\omega }$ and ω are the modulation amplitude of the zero-point energies and the modulation frequency, respectively.